iPad Air 3 Screen Goes Blank But Backlight Stays On

My iPad Air 3's screen goes blank after a few seconds, the backlight stays on and touch works. I connected it to airplay and I can control it and see the image fine. I tried restoring it and nothing happened. The apple store said it'll cost me $349. Can you please let me know what part is broken?

Thank You

It also has three white spots.

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